A dual-range electrical current measurement system is described in U.S. Pat. No. 6,603,301 (issued to Michael Benes and assigned to the assignee of the present application) the entire contents of which are incorporated herein by this reference. That patent represented a significant improvement over what was then the prior art as depicted in FIGS. 1 and 2 thereof. Referring to FIG. 4 thereof, a dual-range current measurement system includes a high-current sensor RH with an associated sense amplifier and a low-current sensor included within a 2-stage amplifier network. This network includes a bipolar current bypass consisting of FETs Q1 and Q2 that together shunt the current being measured to ground when that current exceeds the range of the low-current sensor.
There has been a need for a stable, high-bandwidth dual-range current measurement system that engages a bypass very rapidly when switching to a higher range and settles very rapidly when switching to a lower range.